Imported existing code

libraries/include/boost/signals2/signal_base.hpp

@@ -0,0 +1,32 @@
+// Boost.Signals2 library
+
+// Copyright Frank Mori Hess 2007-2008.
+// Use, modification and
+// distribution is subject to the Boost Software License, Version
+// 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+// For more information, see http://www.boost.org
+
+#ifndef BOOST_SIGNALS2_SIGNAL_BASE_HPP
+#define BOOST_SIGNALS2_SIGNAL_BASE_HPP
+
+#include <boost/noncopyable.hpp>
+
+namespace boost {
+  namespace signals2 {
+    class slot_base;
+
+    class signal_base : public noncopyable
+    {
+    public:
+      friend class slot_base;
+
+      virtual ~signal_base() {}
+    protected:
+      virtual shared_ptr<void> lock_pimpl() const = 0;
+    };
+  } // end namespace signals2
+} // end namespace boost
+
+#endif // BOOST_SIGNALS2_SIGNAL_BASE_HPP